In a case that could have far-reaching implications, a federal judge has ruled that the U.S. Environmental Protection Agency exceeded its authority in revoking permits for a strip mine in West Virginia.

The EPA vetoed the permit for Arch Coal’s Spruce Mine more than a year ago, saying it would cause irreparable damage to the environment. But today (Friday) U.S. District Judge Amy Berman Jackson ruled in favor of St. Louis-based Arch.

She declares a U.S. Army Corps of Engineers water pollution permit for the mine is “valid and in full force.”

As it was permitted, the Spruce Mine would be West Virginia’s largest mountaintop removal mine.